The present invention relates generally to vehicle radios, and more particularly to vehicle radios having station seek functions.
A feature of many vehicle radios is the so-called station seek function, wherein a xe2x80x9cseekxe2x80x9d switch on the radio can be manipulated by a user to cause the radio tuner to automatically change its frequency setting from the current setting to the station frequency closest to the current setting. In other words, by simply depressing the xe2x80x9cseekxe2x80x9d button, a user of such a radio can cause the radio to automatically xe2x80x9cfindxe2x80x9d the station closest to the current station, without requiring the user to rotate a tuner dial and essentially to audibly hunt for the next station. It will readily be appreciated that a seek function is particularly useful in vehicle applications, wherein the user might also be the driver and consequently someone whose manipulation of accessories such as radios is preferably minimized, to prevent unduly distracting the driver from his primary task.
Typically, when a radio""s user manipulates a seek switch, the tuner begins to sweep its frequency, monitoring the received signal amplitude as it does so. When the received signal amplitude is greater than a predetermined threshold (indicating receipt of a station), the tuner stops sweeping. Thus, any signal having an amplitude greater than the threshold will stop the seek function on that signal.
Most of the time the radio will stop on the center frequency of a radio station. It happens, however, that a particularly strong station, in addition to having a strong signal at its center frequency, can also produce relatively strong signals on so-called sideband channels. Also, an interfering signal can be caused by a signal from a relatively weak station that is near the center frequency of a stronger station, i.e., a sideband signal or sideband channel noise can be caused by a weak station. In either case, when the sideband signals are sufficiently strong, a radio in a seek function can be caused to stop on the sideband, before the center frequency is reached. This is undesirable, because sideband signals, while carrying some useful information, typically carry a great deal of unpleasant noise. Consequently, when a radio tuner stops on a sideband, the user must reinitiate the seek function (or manually tune the radio) to cause the radio to be tuned to the center frequency, which is much more pleasant to listen to.
As recognized by the present invention, however, it is possible to cause a radio to continue seeking a xe2x80x9clistenablexe2x80x9d station (i.e., a station with relative signal clarity) upon reception of a sideband signal that would otherwise be sufficiently strong to terminate the seek on the sideband, regardless of whether the sideband is caused by the station or another weaker station broadcasting on a sideband frequency. Accordingly, it is an object of the present invention to provide a system for causing a radio in which a seek function has been invoked to continue sweeping its frequency past channels that contain large amounts of sideband noise. Another object of the present invention is to provide a method and apparatus for causing a radio to ignore sideband signals during seek, without requiring the addition of hardware to the radio. Yet another object of the present invention is to provide a method and apparatus for causing a radio to ignore sideband signals during seek that is easy to use and cost-effective.
A radio includes a tuner that has a station seek function. In turn, the tuner includes a station detect circuit for generating a station detect signal having either a true condition or a false condition. Furthermore, the tuner includes a multipath detect circuit for generating a multipath detect signal having either a true condition or a false condition. The radio also includes a microprocessor electrically connected to the tuner for receiving the station detect signal and multipath detect signal. When the station detect signal is true at a first time and when the multipath detect signal is false at a second time, the microprocessor causes the tuner to terminate the seek function. In accordance with the present invention, the second time is a predetermined time period, e.g., at least about 150 milliseconds and preferably about 200 milliseconds, after the first time.
Preferably, the tuner receives an input signal having an amplitude and one or more frequencies, and the station detect signal is true when the amplitude is greater than a predetermined amplitude. Additionally, the multipath detect signal is true when at least one of the frequencies (after demodulation and detection) is in a predetermined frequency band. In one preferred embodiment, the predetermined frequency band is from about sixty kiloHertz to about ninety kiloHertz (60 kHz-90 kHz). A vehicle incorporating the radio is also disclosed.
In another aspect of the present invention, a computer program device is used by a computer to end the seek function of a vehicle radio. As intended by the present invention, the program device is realized in a critical machine component that causes a computer to perform method steps to end the seek function. Stated differently, a machine component establishes a computer program product for ending a radio seek function. In accordance with the principles disclosed herein, the device can be implemented in logic means on a computer chip. Alternatively, the device can be implemented on an electrical circuit board, or in computer instructions on a machine-readable data storage medium.
The computer program device can include a logic means embodying instructions that are executable by the computer for ending a radio""s seek function. The device includes logic means for determining whether a station signal has been detected, and, if a station signal has been detected at a first time, waiting a predetermined time period after the first time. Then, after the elapse of the predetermined time period, logic means determine whether the station signal exhibits multipath conditions. Per the present method the seek function is terminated if the station signal does not exhibit multipath conditions. A computer-implemented method using the above steps is also disclosed.
In yet another aspect, a tuning device is disclosed for a vehicle radio having a seek function. The tuning device receives an input station signal and generates a demodulated detected signal in response. The device includes a voltage discriminator for generating a first signal when the amplitude of the station signal exceeds a predetermined amplitude. Additionally, the tuning device includes a frequency band detector for generating a second signal when the demodulated detected signal is not characterized by a frequency in a predetermined frequency band. Moreover, processor means are included for terminating the seek function of the radio when the second signal is received a predetermined time period after the first signal is received.
The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: